This invention relates to a semiconductor wafer holding apparatus, and more particularly to a semiconductor wafer holding apparatus applied to an electrical characteristic test unit and reliability test unit for semiconductors (hereinafter, referred to as chips) formed on a semiconductor wafer (hereinafter, referred to as a wafer).
Furthermore, the invention relates to a semiconductor wafer storage chamber which houses a semiconductor wafer holding apparatus.
The process of manufacturing semiconductors requires the technique for transferring wafers from one manufacturing process to another. The technique has been used in a mechanism for transferring wafers in units of carrier and in a mechanism for transferring wafers one by one. As the number of the steps of processing wafers with larger diameters one by one, or the number of sheet-feeding processes, has been increased, the number of the processes of transferring wafers one by one has been increased.
The processes of manufacturing semiconductors include various testing processes. For instance, an electrical characteristic test unit checks a large number of chips formed on a semiconductor wafer for electrical characteristics. On the basis of the result of the test, screening is effected to obtain acceptable chips with the nondefective electrical characteristic. In the assembly process, the screened acceptable chips are packaged with synthetic resin or ceramic.
A reliability test unit checks packaged products for potential defects in the chips by applying temperature and electrical stresses. On the basis of the result of the test, defective products are removed.
As electrical products have been getting miniaturized and sophisticated, chips have been further miniaturized and integrated. In recent years, various mounting technologies for further miniaturizing semiconductor products have been developed. Especially, the technique for mounting unpackaged chips, or chips, has been developed. To put chips on the market, the chips have to be guaranteed quality. For this reason, chips are checked for reliability.
A probing apparatus may be used for a reliability test. With the probing apparatus, however, wafers have to be checked one by one and a lot of time is needed to test one wafer. Therefore, the reliability test using the probing apparatus has a cost problem. In the case of a chip test using a conventional burn-in unit, various difficult problems including an electrical connection between chips and sockets must be solved. The way of handling small chips is very complicated, which can lead to an increase in testing cost.
Therefore, an electrical characteristic test unit and a reliability test unit which have solved the above problems have been wanted.
Reliability test techniques have been proposed in, for example, Jpn. Pat. Appln. KOKAI Publication No. 7-231019, Jpn. Pat. Appln. KOKAI Publication No. 8-5666, Jpn. Pat. Appln. KOKAI Publication No. 8-340030. Of these publications, the first two have disclosed the technique for causing a contactor, such as a probe sheet (e.g., an anisotropic conductive sheet), to make in-unison contact with the chips formed on a wafer reliably without the influence of temperature.
To carry out a reliability test while assuring reliability, it is very important for the contactor to make in-unison contact with the chips on the wafer at high temperatures reliably.
It is also very important to raise the temperature of the wafer in a constant-temperature oven efficiently to a test temperature and keep the test temperature accurately.
Although various techniques for causing a contactor to make in-unison contact with a wafer have been proposed, the technique for controlling the temperature in a constant-temperature oven during a test is not yet fully developed. This has caused the problem of making it difficult to measure the temperature of the wafer accurately during a test and decreasing the reliability of the test.
Before the process of causing a contactor to make in-unison contact with a wafer, it is important for a wafer to be moved smoothly from a transfer mechanism onto a wafer holding table. In a conventional wafer holding table, sufficient steps to cause a wafer to be transferred smoothly from the transfer mechanism have not been taken.
Furthermore, because the wafer holding table in the reliability test unit has been designed for reliability test only, this makes it difficult to use the table in other test units, leading to the poor flexibility.
The technique for causing a contactor to make in-unison contact with the chips on a wafer gives rise to problems with not only the relationship between the contactor and the wafer but also the relationship between the contactor and the construction of the wafer storage chamber. The inventors of the present invention have developed the technique for forming a contactor separately from a wafer storage chamber and causing the contactor to make in-unison contact with a wafer outside the wafer storage chamber and the technique for providing pogo pins to connect the contactor to the electric wiring (the junction terminals) in the wafer storage chamber. The electrical connection technique using pogo pins has the disadvantage that temperature rise during a test prevents the pogo pins from coming into contact with the contactors stably.